Selective Growth of Polysilicon

A chemical vapor deposition (CVD) technique for selective growth of polysilicon has been developed. This technique makes it possible to grow polysilicon only on the exposed silicon without a Si nucleus on the or mask. Perfect selectivity over the whole wafer surface was obtained in a system in the temperature range of 900°–1000°C under a pressure of 100 Pa at a significantly high line velocity. These conditions provide a perfectly selective silicon epitaxy technique, while addition of trichloroethylene as a gas that causes extreme deterioration of the crystallinity produced the selective polysilicon technique without a degradation of selectivity. A SEM observation showed that the grain size of the grown film was about 0.3 μm. SIMS analysis indicated that the concentration of carbon atoms incorporated in the film was on the order of 10 20 cm −3 . X‐ray rocking curve analysis derived a smaller lattice parameter of 5.425A, due to incorporated carbon atoms.